When only one scanner detects something out of all of the scanners on virustotal (58 I think), then there is a high likelihood that it is a false positive detection.
You say this is an avast file, yet there is no information it belongs to Avast in your post or image. I don't see that file in my Avast installation, where did you find it, what found it (or what made you upload it to VT) ?
It is preferable to just post a link to the virus total results as that can be interrogated, and image can't.
In an earlier VT scan nothing was found, 2018-10-31 22:06:55 UTC.
https://www.virustotal.com/#/file/22718fce040817872f335d214fdc2bfc0f6999f96e591397ebca7db84dc97028/detectionAvast does use a stub installer for users that want to do an on-line install, I prefer to use the full off-line installation file
The stub installer, I don't know if it is called that or this avast_free_antivirus_setup.exe, see attached image.
