Problem challenge validation

Hi,
The practical challenge validation has a problem that I haven't been able to solve for a few days. I already accumulate three modules without being able to perform the validation:
1. Data Modeling > Create Object Relationships (Accuses: The field 'Contact__c' either does not exist on the Offer__c object or it is not a lookup relationship.)
2. Data Management > Import Data (Accusation: Couldn't find the contact records from the CSV file. Make sure you imported the CSV file correctly.)
3. Data Security > Control Access to the Organization (Accuses: The new user does not have the System Administrator profile. In the User Record Profile field, choose System Administrator.)
Solutions already tried:
- Open a help case and asked to look for answers in the community (Trailhead challenge)
- I looked for help on the Trailhead Challenge, found help links that didn't help to solve the problem:
1. https://trailhead.salesforce.com/pt-BR/trailblazer-community/feed/0D54S00000DfFkjSAF
2. https://trailhead.salesforce.com/en-BR/trailblazer-community/feed/0D54S00000A97VmSAJ
3. https://trailhead.salesforce.com/en-BR/trailblazer-community/feed/0D54S00000EnjBTSAZ
- I redid the tests from the beginning in the same playground organization;
- Created new playground organizations and redone the tests;
I changed the language;
None of these features worked, can you please help me?