baby steps to create Captive Portal

hello, hope you are doing well

i'm new so kindly be patient with me with being said i got 3 questions

1- the connection between SW->APs tagged or access ?

2- i fellow the steps in youtube for NMS2500 to create a Captive portal yet it's not working either STA successfully connected to APs with password or blank-page pops-up without any info and the connection is dropped ?

3- i read installation instructions for R4.8 fully but no mentation of how to set up the captive portal parameters -URL-IP-..etc ..

bottom of line really need help to set up captive portal