@JeskoGoesVROOM Thank you sir!

1. select a part in the designer
2. press the button with the arrow on it (it's like that for me, might differ between devices)
3. press the top button, which resembles two cable connectors
4. bam, you are in the connection menu
5. to connect stuff, select a part you want to connect, in the menu, click "add connection", choose one of those blue arrow things, press confirm or whatever
6. now, go and find the part that you want to connect, click on that, click on any one of the blue arrow things again, press confirm
7. bam, you've made a connection