Hi @Wassini ,
Could you please share a bit more about your scenario?
Does your external company belong to same Tenant/Org as your current company?
Based on the issue that you mentioned, I think your external company and your current company are in different Tenant/Organization, is it true?
Currently, within PowerApps, you could only share apps with users or security Groups within your Organization or the whole Org. You could not share apps with external organization.
More details about sharing apps within PowerApps, please check the following article:
Share an app
If your external company and your current company are in different Tenant/Organization, you could not access these apps created in your external company.
If you want to use these apps created within your external company, you could consider ask your external company to export these apps into package files, then share the package files to your current company. On your current company, import these package files into your PowerApps.
More details about exporting or importing canvas app across environments, please check the following blog:
https://powerapps.microsoft.com/en-us/blog/powerapps-packaging/
In addition, as an alternative solution, I think the Solution could also achieve your needs. You could ask your external company to create a Solution within their PowerApps, then within this Solution, create their apps. After that, they could export this Solution and share it with your current company, then you could import this Solution within your PowerApps.
More details about Solutions in PowerApps, please check the following article:
https://docs.microsoft.com/en-us/powerapps/maker/common-data-service/use-solution-explorer#add-an-existing-component-to-a-solution
Best regards,