Hi friend!
Before logging in to an AP through the web platform, connect a terminal to the AP using an Ethernet cable or in wireless mode to ensure that they are reachable to each other. Then you can log in to the AP using a browser.
You can refer to the link https://support.huawei.com/hedex/hdx.do?docid=EDOC1100192519&id=EN-US_XTASK_0176909507&lang=en
Hope it helps you!