Cannot use free Teams anymore

Hi,

I have the following situation:

- I created an Office 365 E3 tenant

- I added my Microsoft-Account as a guest user to this tenant

- I assigned a Teams-License to that guest account

- I decided to not use O365 anymore, so I canceled the subscription

- I deleted the guest account from the O365 tenant

Now when I want to login to teams with the Microsoft-Account, I get the following message.
AADSTS50020: User account 'xxx@outlook.de' from identity provider 'live.com' does not exist in tenant '<O365 tenant name>' and cannot access the application '<tenant id>'(Microsoft Teams Web Client) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account.

How can I solve that issue to be able to use the free version of Teams?

Thanks!

Markus