Hi Taryn,
Please see the following for licensing requirements:
Protect your sensitive data with Microsoft Purview (Licensing)
https://learn.microsoft.com/en-us/purview/information-protection#licensing-requirements
You will need a Microsoft 365 Business account to be able to purchase the necessary licensing.
You will need Microsoft 365 E3 or E5, Office 365 E3 or E5. The + sign indicates that it can be added onto that license type that it is matched too.
Microsoft 365 enterprise plans
https://www.microsoft.com/en-us/microsoft-365/enterprise/microsoft365-plans-and-pricing
Sign up for a Microsoft 365 Business Standard subscription
If this is helpful please accept answer.