Try going direct to the team join link - here ? Might have to tweak parameters, not sure.
Try logging out of the Primaboinca site, removing any cookies for that site, then logging back in and seeing if the link then appears.
I've just tried on Primegrid (one of the very few where I'm not founder) and it didn't seem to clear my cookies very well at all and got confused when I went to my team page to rejoin. When I refreshed I was still a member of the team! Tried it again but cleared cookies too for the primegrid site and then it worked.
YMMV
I hope you don't find this offensive but sometimes pictures work better. Click images to enlarge.
Search for SETI.USA
Prima-1.jpg
Click on Team Link
Prima-2.jpg
Click Join Team Link
Prima-3.jpg
It took me forever to find the link the first time I tried to join the team on a project. If the "Join Team" link just isn't there then maybe report the problem the the project admins. Be sure to include your OS & browser info.
Images always help
I think in this case though it's a bug in the webcode where it's sometimes not displayed for whatever reason. I've had quite a few requests about it on various projects, though the team_join.php link has usually worked, I think they altered this in recent builds.
Thank you for the photo's, and no worries I am not easily offended. As I have joined the team on every other project, the link has been available to click every time. Just for some reason, it is not showing up for me on 3 different computers that are in different locations. So this is what I was seeing:
But never fear!! I was able to join via my phone.
Strategery.....