I suggest you look into the 'data files' option in LoadRunner Cloud, please check this page on the help center:  https://admhelp.microfocus.com/lrc/en/2022.06/Content/Storm/Data-Files.htm#mt-item-0

Another option is to deploy VTS Server in an environment that is accessible for the Cloud LGs. 

I suggest you explore the data files solution first.  

I understand the concept of providing data files to a script for parameter values. My question is really about generating custom log files based on information that the Vugen scripts capture DURING the load test. Therefore, these log files contain information that CANNOT be defined before the Vugen script is executed in the Loadrunner cloud.

Since the Vugen scripts that create the custom log files may be different depending on which Load Generator the Vugen script is executing on, the question of HOW or IF these custom data files can be accessed AFTER the load test is finished is what I need to know.

It may not even be possible  or feasible depending on what storage restrictions exist for any Vugen script on the cloud-based load generator system on which it is executed.

If the custom data can be incuded in Vuser log file, one option is to write them via lr_xxxxxx functions (for example: lr_output_message) and enable the "Collect Vuser logs from cloud-based load generators" option in load test. After test run, the Vuser log files can be downloaded from LRC. (each Vuser has a separare log file)