Can we add them to our resume?

[pvitalsolutions]

Hello,
I wanted to ask that can we add the companies that we worked for on fiverr on our resume. Like suppose, a person hired me who works for an ‘‘XYZ’’ company, he needed some work done for his company. After the work is done, can we add to our resume that we worked for that company. Is it allowed? As far I think, there is no harm in adding but still wanted to be sure. Please let me know.
Thank you