As 3.0.0 is from times of before sunset of bintray it could be that the links that are used in update.ps1 point to a location that is not available any longer.
From your description it is not clear if the download successfully completed or if it is aborted.
What are the links that are used in the update.ps1 file ? Where do the DownloadLocation variables point to ?
Running command to extract rows containing string http:
grep http runtime/bin/update.ps1
results in:
$DownloadLocation="https://ci.openhab.org/job/openHAB3-Distribution/lastSuccessfulBuild/artifact/distributions/openhab/target/openhab-$OHVersionName.zip"
$AddonsDownloadLocation="https://ci.openhab.org/job/openHAB3-Distribution/lastSuccessfulBuild/artifact/distributions/openhab-addons/target/openhab-addons-$OHVersionName.kar"
$DownloadLocation="https://www.openhab.org/download/milestones/org/openhab/distro/openhab/$OHVersionName/openhab-$OHVersionName.zip"
$AddonsDownloadLocation="https://www.openhab.org/download/milestones/org/openhab/distro/openhab-addons/$OHVersionName/openhab-addons-$OHVersionName.kar"
$DownloadLocation = "https://www.openhab.org/download/releases/org/openhab/distro/openhab/$OHVersionName/openhab-$OHVersionName.zip"
$AddonsDownloadLocation = "https://www.openhab.org/download/releases/org/openhab/distro/openhab-addons/$OHVersionName/openhab-addons-$OHVersionName.kar"
Write-Host -ForegroundColor Green "Check https://www.openhab.org/docs/installation/windows.html"