Power Automate - Merge PDFs not working

Hello all,

I'm trying to simply Merge an array of 3 dynamic PDFs from Sharepoint, but when it comes to the Adobe Merge PDFs action, it simply stalls out and does not work - what am I doing wrong? Any guidance here would be very much so appreciated! I've been following these two resources:

https://blog.developer.adobe.com/merging-documents-using-microsoft-power-automate-69a68e46081b
https://community.adobe.com/t5/acrobat-services-api-discussions/merge-pdf-power-automate/m-p/14347140

to no avail, sadly.