I began my journey in swallowing the red pill and the first thing I'm doing is lifting, I downloaded the JDC fitness guide for begginers where I train 3 days a week and 4 days off and in a the guide they recommend not doing any other exercises and just to rest, the problem is I'm a regular mountain Biker, I'm 22 years old 5'11, 71kg. Skinny as fuck.

So my question is Can I make an exception and go mountain biking at least 1 day a week??

Edit: I'm not asking for permission, I'm asking for advice regarding what is beneficial to gain muscle and strength or not due to my lack of knowledge in fitness.