@Adamh44
This requirement to get customer profile data from 3rd party system (Salesforce CRM in this case) is quite similar to one discussed here: https://experienceleaguecommunities.adobe.com/t5/adobe-target-questions/oracle-eloqua-and-adobe-targ...
You have few options:
1. Injest profile data from CRM into Target using Customer Attributes or Bulk Profile Update API and using EC ID service, attach crm id to the user profile for targeting.
2. Use Data Providers to make an API call to CRM and fetch data in profile parameters, create audiences in Target accordingly.
3. You can also injest the crm data by creating data sources in Audience Manager or Experience Platform and the audiences become available in Target through cloud integration though these would require additional provisioning and integration expertise.