Hi @Lucikana,
This section of the app would not go over cleaning your machine, and will be a general help section with a few brief resources which include "What is the Dyson Link app?" "How to add a machine to the Dyson Link app" and "How to remove a machine from the Dyson Link app."
In this case, if you are looking for info on how to clean your machine, we generally would advise changing out your filter as recommended by your machine. Outside of filter replacement, the outside of the filter shroud can be cleaned with a soft cloth, or vacuumed out with a soft bristle brush attachment – or just a soft bristle brush on its own.
I've also included a resource from the community to provide additional resources on cleaning your machine. Alternatively, instructions with a visual on cleaning your unit may be found by clicking the settings icon at the top right corner of the main control page of the Dyson Link app. The main page is where you will control your machine directly, and see your air quality, readings. Once you click on the settings icon, instructions can be found by selecting the third option, titled "using your machine." You may then select the fourth option down titled "cleaning your machine" for additional information.
An additional recommendation for the unusual error being experienced would be to reset the mobile device being used to see if this helps in resolving the issue.
If you have any further questions, please don't hesitate to let me know. Alternatively, we also welcome you to contact the country specific Dyson helpline number listed on your machine. In this case, it looks like you may be located in Malaysia, from what we see on your public profile. I've included contact details for you as well below, if you prefer.
https://www.dyson.my/support/contact-us