That click is for moving from slide to slide manually by pressing the mouse click. That's the default.
I understand that it will have to be placed at the end of the video to stop and click to move to the next slide.
Is there any way to place it automatically at the end of the video, or do I have to move it manually?
If you have such a requirement on each slide, it would be better to use a shape button on the main master slides. Its advantage would be that it will pause each slide at its last frame. You cannot use a click box, but the smart shape can be made 'invisible' by setting Opacity and Stroke width to )<
If you insist on using that click box, move it to the end or extend its duration till the end of the slide by using CTRL-E. The pausing point of a click box is always at the end of its timeline.
Maybe you'd need to read this blog post, the most important I ever wrote (look at the number of views):
https://blog.lilybiri.com/pausing-captivates-timeline