Instructional Design and Digital (online) Onboarding in a Fast Growing Start-Up Company

Dear e-learning heroes,

I work since recently in a fast growing start-up company as an Internal Instructional Designer and e-learning developer with the goal to develop digital onboarding and continuous learning of new employees. 

I have always been in a team when designing and developing the e-learning courses for external customer and this is the fist time I have to deal alone with many internal needs my company has. 

Working as an instructional designer in a fast growing start-up company is very exciting and motivational job but includes also some challenges: 

• the culture is still overly oral so I have a hard time to collect the contents, written material and get the inputs for my courses 
• the information about the business, processes, and products are constantly changing and evaluating so there is constantly need for updates...
• employees are so busy because of the quantity of the work to be done that it's difficult to get collaboration of my internal "SMEs" to work on design and validate my storyboards, courses.

Is there anybody being in the similar situation as me?  If yes, how do you deal with the difficulty to get the inputs, get the collaboration and develop online learning in fast growing start-up company?  Any recommandation on ressources to be considered? 

Thanks so much for sharing your experiences!