From the Market?If you are on Windows (if your PC is on Linux or MacOS so the Market will not work with them) so you can check the information I collected -
How to buy/sell robot https://www.mql5.com/en/forum/9950/page74#comment_2694942
Tips for Purchasing a Product on the Market. Step-By-Step Guide - the article
how can i down load an expert advisor for demo testing from the markethttps://www.mql5.com/en/articles/586
Where can I see my purchases? https://www.mql5.com/en/forum/9950/page70#comment_2564931
How to Install an Earlier Purchased Applicationhttps://www.metatrader5.com/en/terminal/help/market_buy
Besides, you can check in Metatrader - it may be already was installed ...