Choosing package for download
The question arises: why don't we provide a single download like WHMCS? Mainly for two reasons but first let us give a little bit of background.
For sure you noticed that downloading WHMCS doesn't require you to choose a package depending on your PHP version. Files are in fact encoded to support all versions of PHP starting from 5.6. It's all plain and simple but there are drawbacks.
File SizeA PHP file encoded to support so many versions of PHP can increase its size up to 80%! Here is why WHMCS full install is now more than 160 MB while just few years ago it was well below 100 MB.
PerformancesHaving bigger files also mean that scripts run slighly slower.
It's more efficient to "forge" files that perfectly suit your system. For instance there's no point in having backward-compatibility for PHP 5.6 when you system runs on 7.2. On the contrary if you're using the outdated 5.6 which is already slow, bigger files will worsen your performance even more.
That being said, you should always prefer to download the specific package that runs on your system and ignore the Bundle option which is the one that supports all versions of PHP. Using Bundle is not the end of the world but now you know the story behind it.
You can check your PHP version from the backend of WHMCS. Navigate to Utilities > System > PHP Info. In the next page right below PHP logo you'll find your PHP version.