Steps to import from other CMS to AEM
1. Move the assets to S3 or Azure blob storage from existing CMS platform
2. Create a metadata csv file to retain all the metadata information
3. Use Bulk Import tool provided by ACS commons to import the assets from S3 or Azure
4. Use CSV importer for importing the metadata information created in step 2
5. Verify the count of assets before and after using the querybuilder query in AEM.
Bulk Import: https://experienceleague.adobe.com/docs/experience-manager-learn/cloud-service/migration/bulk-import...
Data Importer: https://adobe-consulting-services.github.io/acs-aem-commons/features/mcp-tools/data-importer/index.h...
Make sure the folder path remain same in S3/Azure which you wanted in AEM to be stored.
Hope this helps.
Please follow this link
https://experienceleaguecommunities.adobe.com/t5/adobe-experience-manager/dam-migration-from-another...