I understand. This actually does not happen normally. There can be folder permission issue as well.
In one of the exceptional cases before, using cpanel did not help either but the following method helped. Can you please try that once?
You can upload all files from helixultimate_quickstart_j3_v1.1.1.zip
templates\shaper_helixultimate
plugins\system\helixultimate
Then "Discovery" > "Install"
If it still doesn't work, kindly provide your administrative access using the hidden mode to share the log in credentials.