If the invitation isn't on the Samsung Members App @cezar0408 then unfortunately the invitation to join isn't available.
Please be aware if your not already that Beta testing can cause bugs in the phone and stop some apps from working such as banking apps etc.
It isn't advised to download a beta onto your daily driver i.e main phone you need to have stable and working properly. [ apologies if your aware of this ]
Daily Driver > Samsung Galaxy s²³ Ultra 512Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
