@LaurelLee
Yes, you can use Roku Streaming players (like the Express) and other brand streaming players with your RokuTV.
Can you provide more detail of your issue. Were you able to setup your RokuTV and it is just currently unavailable to connect to internet. What is your router model number, your ISP (internet service provider), your Roku OS (Settings/System/About), and are you seeing your network(s) available in the connection screen.
I am thinking with the inability of your Roku Express being unable to connect that you may have a known cable ISP router issue in which you will have to modify the settings under your 2.4ghz band. (this is the band your Roku Express operates on.)
If you have Xfinity/Comcast, Cox, or AT&T as your ISP, then you may need to change your wireless mode to b/g/n in order to be able to connect your Roku Express. (Edit your 2.4ghz Settings)
Xfinity / Comcast → ( https://www.xfinity.com/support/articles/change-wifi-mode-admin-tool-xfinity-xfi ) with a walkthrough ( https://community.roku.com/t5/Network-Wireless-Wired-Connections/Error-014-30-stuck-for-three-days/m...)
Cox → (https://www.cox.com/residential/support/managing-your-in-home-network-with-my-wifi.html)
AT&T → (https://www.att.com/support/article/u-verse-high-speed-internet/KM1046172). You can select your appropriate router from the drop down menu.
----
Feel free to post back with an update or if you need more help.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102