Multiple steps each with a tasks vs one step with multiple tasks (for the user)

I am sketching the user flow for a new feature of a fitness/medical recovery application that is using hardware sensors to monitor the way the user is performing certain fitness exercises.

In order for the user to begin the training he has to perform certain tasks before:

• position the sensors (two sensors) on the body or on a limb (i.e hand scenario), above and below the elbow
• be sure that the sensors are in a certain position (there are some LEDS* on one side of the sensors and they must face up)
• have the sensor centred on the body or on the limb
• strand the straps so the sensor/s does not fall off

If I place all of this in a single screen I am afraid there may be too much information and the screen may end up with a high cognitive load. I would like to split this in multiple screens and after the user goes through this at least 2-3 times, wrap it up in a single screen as the user will be familiar with the process.

Currently I am in an argument regarding splitting the screen, as mentioned above. The team has a solid point against splitting the screen into mutiple screens: the "onboarding process" until the user can start training, beside this screen, contains 6-7 more screens. From these 6-7 screens at least 4 require the user to do at least one action (i.e. move a the limb with the sensors).

If the user does not perform these tasks successfully the hardware device won't track his movement therefore the tasks are mandatory. From my point of view, I'd rather have the user go 1-2 times through a longer flow and be able to successfully use the product rather than keeping it simple and confusing the user.

Important: Our users are of an older age demographic therefore everything must be as simple and clean as possible.

What would be the best approach to keep the process as short as possible while maintaining its usability? I haven't seen any other application that has anything as complex as what I mentioned above.

*the LEDS task is tricky because it is not too visible on the sensor. Beside the phrasing "LEDS must face up" is confusing. Last but not least, our users may not even know what's a "LED".