I had used Grammarly before, but I now use Pro Writing Aid, there is a nice free addon you can install in Microsoft word too. I found PWA very helpful in many ways when checking my manuscript. It did a basic check which found initial errors in grammar, spelling, passive voice, and readability improvements. There are also other reports that show style issues, sentence length variation, overall glue word percentage of a passage or chapter, over-dependence on adverbs, over-complicated sentence construction and repetitiveness of words used. A lot of the stuff I didn't even notice until it was pointed out.
There is a free and pro version just like Grammarly. I got the pro version for 1 year and was able to open my scrivener project in Pro Writing Aid and could make changes and save them directly to the scrivener project file.