How do I view collaborations in Buyer account
What kind of collaboration do you want to see?
Depending on how your buyer company was set up everytime a supplier responds/collaborate with you a work item will be created and you can see it on top right of your screen, next to your username initials.
Also you can click in View on the upper left menu. Inside this menu you can list all your Job Posting, Job Seekers, SOW, Work Orders or Worker and follow-up them.