Very interesting !!. DOAJ is a highly prestigious J. not driven by APC . So as per my openinon the quality of research is independent on the Journal IF . So you need not not worry that any J driven by high APC can't be afforded untill APC is fully waived .

My personal understanding is that quality of journal does not mean it is a paid journal or not. Some very high quality journals in different fields can be free.

Karwan Mustafa Saeed I completely agree with you, but I can provide you with the names of some journals(Q1, Q3/SCIE index) where you publish average-level papers by paying hundred/thousand dollars. At the same time, I can give you names of (Q1, Q3/SCIE) journals that publish the only high-standard paper. The money factor matters and I have seen few researchers using it for their academic progress.

So, my question is if those papers are the same or lower quality than mine are index in Scopus/WoS just because the author has money to pay. Can I say that these DOAJ journals that publish papers with no APC are of similar or higher quality?

PS:

When I look few institution requirements it seems that they don't even consider other indexing than Scopus or SCI/SCIE. Even if the faculty member is publishing average quality papers by paying huge sums of money.

For a beginner independent researcher like me which lacks the knowledge to publish in higher-level journals and money to pay for paid ones, it is a huge disadvantage.

Few researchers for Australian University have told me that they consider only Q1/Q2 or SCI index paper.

Yes, you are right as well. As authors with not much financial support, we all have these challenges.