Users at Ursa Major Solar are trying to create Opportunities.
When populating a custom picklist field, the users receive errors. Additionally, when the users select either of the two values in the picklist, they receive different error messages above the field and are unable to save the Opportunities.
Why is this error likely occurring?

If your org is configured for data export, you can generate backup files manually how often?

Record locking prevents users from editing a record only if they have certain field-level security or sharing settings.

If single sign-on is enabled for your organization, API and desktop client users cannot log in to Salesforce CRM unless their IP address is included on your organization’s list of trusted IP addresses or on their profile, if their profile has IP address restrictions set.

At Universal Containers, a user's department determines which fields the user can see and edit on Opportunities. For example, users on the Sales team can edit all fields on the Opportunity, while users on the Support team have read-only access to these fields.
In which location is field-level security controlled for users on these teams?