test2.txt document is correctly uploaded but in '/' repository, not in '/Sites/0/documentLibrary/CERTs' folder.
My ACS instance is running on Community 7.1.0
The correct way is the below examples, you have to provide the site (testsite is the siteshortname and myfolder after documentLibraryis the folder where file needs to be uploaded) with foldername path for relativePath param, see example below:
$ curl -X POST -F email@example.com -F "name=somefile.txt" -F "nodeType=cm:content" -F "cm:title=My text" -F "cm:description=My text document description" -F "relativePath=/Sites/testsite/documentLibrary/myfolder" http://localhost:8080/alfresco/api/-default-/public/alfresco/versions/1/nodes/-root-/children?alf_ticket=TICKET_455c2e0153a24170466005a9b9326607cee59674
$ curl -X POST -F firstname.lastname@example.org -F "name=somefile.txt" -F "nodeType=cm:content" -F "cm:title=My text" -F "cm:description=My text document description" -F "relativePath=/Sites/testsite/documentLibrary/myfolder" -H 'Authorization: Basic VElDS0VUXzQ1NWMyZTAxNTNhMjQxNzA0NjYwMDVhOWI5MzI2NjA3Y2VlNTk2NzQ=' http://localhost:8080/alfresco/api/-default-/public/alfresco/versions/1/nodes/-root-/children