Module "Related products pro" during its installation process installs database and associates module with positions (hooks) in prestashop. Below you can find detailed information about installation procedure, what module does and what parts of installation are required.
Database installation
module creates new tables in shop's database (sql):
These tables are required . Without them - you will not have possibility to manage "lists of related products", create new instances of "related products" etc. Simply saying - module will not work at all.
Hook Associations
Depending on version of your prestashop module associates itself with positions listed below the picture. You can manage associations with positions in shop's back office under design > positions page (prestashop 1.7) or under modules > positions (in PrestaShop 1.6).
All of these positions are required. Our module to create "related products" on product pages will not work correctly if it will not be associated with all of them. The rest of hooks are requried for module appearance in your shop's front office and also its workflow in shop's back office.
Where to manage module in shop's back office?
Module has own configuration page available on modules manager page (modules > modules). You can "configure" module main features there, the way of how it behave globally and control the most important settings from addon's workflow point of view
As you probably know each product can have own unique "related products pro". To manage lists of "related products" just go to product edit page and go to "modules" section. You can manage there list of "related products" - create new, edit existing etc. You can create there lists of "related products individually for each item or create "global" blocks that will appear on many product pages.