How do I access same documents on other devices? (I want to acess the documents, which were edited on PC, on mobile.)

Please sign in to Polaris Office and save your documents at My Polaris Drive, and then you can see them at other device when you sign in to Polaris Office with same email account at other devices.
The My Polaris Drive is a cloud storage provided by Polaris Office, you are able to save documents in My Polaris Drive.
You can check documents saved in My Polaris Drive when you sign in to Polaris Office with same email account.

* If you save the document in local device not My Polaris Drive, you cannot check the document on other devices.
* If the Internet environment is not good, the sync in My Polaris Drive may take some time.
* You can use this features on Polaris Office Cloud, you can't use it on Polaris Office Mobile and Lifetime version.