I cannot add a teammate

Ask your colleague to start the @hints_crm_bot first. The app will 'see' your colleague, and then you can invite. After that, the colleague needs to go to the @hints_crm_bot and accept the invite.

I have added a teammate, but the link expired

No worries, revoke the invitation in the 'Invite Team' menu and send it again. Also, make sure that your colleague has started the app @hints_crm_bot, otherwise, the bot will not 'see' your colleague.