Login information in the invitation email "Welcome to Teachme Biz!" does not have an expiration date.
The information can be used even after time has passed.
* No invitation email will be sent in the following cases
- No email address was registered when the invitation was sent
- Registered using the CSV Batch Registration function without checking "An e-mail is sent to added users after registration is complete."
If unable to log in using the information provided, the following possibilities exist.
- Group ID was changed
- Account Name was changed
- Password was changed
- User was deleted or suspended
Related: I can't log in. What should I do?
https://help.teachme.jp/hc/en-us/articles/900005507706