I do believe you will be able to handle this volunteer work. They will be flexible to your needs. I think they will be happy to have you there helping them as a volunteer. They can use all of the help ther can get.

I am thinking of volunteering myself with this group who salvages or fixes personal computers. If I stay doing this long enough, the company will set up a PC of my own. They also have volunteers who help others to use the PC. This will add structure to my life and allow me to be productive, the first time in two decades. If this works out, then I will search for an actual paying job.