Update Column in Document Library based on folder name

We want to create a workflow changing the column "project ID" in a document library; based on the foldername. So it will enable us to have the correct information in the "project ID" field without editing all documents manually.

Current situtation:

• We upload documents to a library trought the file explorer (through sharepoint Sync)
• These documents are uploaded in a folder with a name, the same as the "project ID"
  e.g. https://collaboration.DOMAIN.com/sites/NAME_SITE/AssociatedDocuments/352/Document.docx

So in the example the Project ID should be changed to 352. 

Thank you very much for your help and support!