Inclusion Criteria:

1. Subject voluntarily gives informed consent to participate in the study.
2. Males and females aged 18 years or older at the time of informed consent. a. Females of reproductive potential must be non-pregnant (as confirmed by a urine pregnancy test at screening) and non-lactating, and will: i. Either abstain from intercourse (when it is in line with their preferred and usual lifestyle), or ii. Use two medically acceptable, highly-effective forms of contraception for the duration of study, and at least 30 days after discontinuing study drug. b. Males with a partner of childbearing potential must use a condom for the duration of treatment and for at least 48 hours after discontinuing study drug.
3. The subject has a confirmed diagnosis of WHO Group 3 PH based on CT imaging, which demonstrates evidence of diffuse parenchymal lung disease performed within 6 months prior to randomization. Subjects may have any form of ILD or CPFE.
4. Subjects are required to have a right heart catheterization (RHC) within one year prior to randomization with the following documented parameters:
   1. Pulmonary vascular resistance (PVR) > 3 Wood Units (WU) and
   2. A pulmonary capillary wedge pressure (PCWP) of < 15 mmHg and and
   3. A mean pulmonary arterial pressure (mPAP) of ≥ 25 mmHg
5. Baseline 6MWD ≥ 100 meters
6. Subjects on a chronic medication for underlying lung disease (ie, pirfenidone, nintedanib, etc) must be on a stable and optimized dose for ≥ 30 days prior to randomization. Subjects receiving pirfenidone or nintedanib must have been receiving treatment for at least 90 days and on a stable dose for at least 30 days prior to randomization.
7. In the opinion of the Investigator, the subject is able to communicate effectively with study personnel, and is considered reliable, willing and likely to be cooperative with protocol requirements, including attending all study visits.
8. Subjects with connective tissue disease (CTD) must have a Baseline FVC of < 70%.

Exclusion Criteria:

1. The subject has a diagnosis of pulmonary arterial hypertension (PAH) or PH for reasons other than WHO Group 3 PH-ILD as outlined in inclusion criterion 3.
2. The subject has shown intolerance or significant lack of efficacy to a prostacyclin or prostacyclin analogue that resulted in discontinuation or inability to effectively titrate that therapy.
3. The subject has received any PAH approved therapy including: prostacyclin therapy (i.e., epoprostenol, treprostinil, iloprost, or beraprost; except for acute vasoreactivity testing), IP receptor agonist (selexipag), endothelin receptor antagonist (ERA), phosphodiesterase type 5 inhibitor (PDE-5I), or soluble guanylate cyclase (sGC) within 60 days of randomization.
4. The subject has evidence of clinically significant left-sided heart disease as defined by:
   1. PCWP > 15 mmHg
   2. Left ventricular ejection fraction < 40%.
   Note: Subjects with abnormal left ventricular function attributable entirely to impaired left ventricular filling due to the effects of right ventricular overload (i.e., right ventricular hypertrophy and/or dilatation) will not be excluded
5. The subject is receiving > 10 L/min of oxygen supplementation by any mode of delivery at rest at Baseline.
6. Current use of any inhaled tobacco/marijuana products or significant history of drug abuse at the time of informed consent.
7. Exacerbation of underlying lung disease or active pulmonary or upper respiratory infection within 30 days of randomization.
8. Initiation of pulmonary rehabilitation within 12 weeks prior to the randomization.
9. In the opinion of the Investigator, the subject has any condition that would interfere with the interpretation of study assessments or has any disease or condition (ie, peripheral vascular disease, musculoskeletal disorder, morbid obesity) that would likely be the primary limit to ambulation (as opposed to PH).
10. Use of any investigational drug/device, or participation in any investigational study with therapeutic intent within 30 days prior to randomization.
11. Severe concomitant illness limiting life expectancy (< 6 months).
12. Acute pulmonary embolism within 90 days of randomization.