Content deployment for module fails: Upload application content failed

I keep getting this error when I try to deploy my app in cf:

[Activity_Sampler_Service_Admin_ui_deployer] [ERROR] Upload application content failed { CODE: '1001' } validation error: Invalid file format. The request body must include a zip file that contains a zip file for each HTML5 application.

mtad.yaml:

- name: Activity_Sampler_Service_Admin_ui_deployer
  type: com.sap.application.content
  path: Activity_Sampler_Service_Admin_ui_deployer
  requires:
  - name: Activity_Sampler_Service_Admin_html_repo_host
    parameters:
      content-target: true

mta.yaml:

 - name: Activity_Sampler_Service_Admin_ui_deployer
    type: com.sap.application.content
    path: .
    requires:
      - name: Activity_Sampler_Service_Admin_Admin_html_repo_host
        parameters:
          content-target: true
    build-parameters:
      build-result: resources
      requires:
        - artifacts:
            - ActivitySamplerServiceUI5-content.zip
          name: ActivitySamplerServiceUI5
          target-path: resources/

In the resources folder, there is a zip file with the corresponding name:

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