I've succesfully installed PDF-Xchange via Wine and it runs very well, but i would like to make it my default pdf viewer app on zorin-os. The .desktop app runs smooth, but it won´t appear on the app list to make them as default app for pdf files.
You should be able to do so by right-clicking the file, clicking Properties and selecting the program as default in Open with. When you first launched a PDF with that program it should have been already listed.
If you are just using an app for viewing, I would recommend Okular as a better alternative. It is what i used from lockdown until retirement, extracting text from pdf into .docx files for students with low vision, using SoftMaker Office 2018/2021.
too bad linux don´t have a top notch pdf editor. i use pdf-xchange on windows, it´s even better than adobe acrobat. i´m lawyer and i use pdf alot, so pdf-xchange is a nobrainer for that role.
GNU/Linux has two commercial pdf edtors, Master PDF Editor and pdfStudio Pro. I own the latter and had to use it to modify an AS Physics paper being used in a mock exam, shortly before I retired. It costs around one-fifth the price of Adobe Acrobat and unlike Adobe Acrobat which sells add-ons, pdf Studio Pro by Qoppa Software (now owned by Apryse) has all the bells and whistles included.