This isn't about a return on investment.

As the examples below show, ROI stands for Regulamentul de ordine interioară. Literally that's "Internal Regulations", but in English, I don't see any need to add "Internal", which goes without saying - just "Club Rules/Regulations" (or even "Rules and Regulations") would do. So what your sentence means is that these rules/regulations state - among other things - what bonuses are paid to the footballer if the team wins away or at home, or is promoted to the Second Division (Liga 2).

Here's an example of the abbreviation in a football player's contract:

a) De asemenea sportivul nu poate evolua în competițiile de minifotbal, ori alte competiții în afara celor în care participă clubul la care este legitimat, fără acordul prealabil al clubului de care aparține, conform R.O.I.
(...)

c) R.O.I. pentru a avea valabilitate, trebuie să fie înregistrat la FRF/AJF.
https://www.frf-ajf.ro/upload/bh/files/Contract_Activitate_S...

Later in that document, we find a sentence similar to yours (likewise about bonuses) which explains exactly what ROI stands for:

Prime de joc acordate conform Regulamentului de ordine interioara.
https://www.frf-ajf.ro/upload/bh/files/Contract_Activitate_S...

Another example:

prime de joc conform Regulamentulu de Ordine Interioară

(...) la această sumă adăugându-se salariul și bonusuri de victorie, conform ROI.
https://unupetrotus.ro/exclusiv-cati-bani-i-a-pus-pe-masa-co...

And here are two examples of "Club Rules" of English football teams:
https://www.cullercoatsfc.co.uk/wp-content/uploads/Club-Rule...
https://www.alexandraparkfc.co.uk/the-club/alexandra-park-fo...