There may be a workaround; however, given your description, my recommendation is to return the computer to the store for a refund, buy another model, and write to Acer telling them why you returned the computer. Here's why, along with some caveats....
With Windows 8.x, Microsoft required that computers based on x86 and x86-64 computers enable users to disable Secure Boot. The option would sometimes be hidden or lurk behind a scary warning, but it was there. With Windows 10, Microsoft has made disabling Secure Boot optional. To date, reports I've seen have indicated that it's still there, so (caveat #1) you may want to review your firmware settings, keeping in mind that the option to disable Secure Boot could be hidden somewhere -- maybe it's visible only after you change another setting, for instance. The key here, though, is that if the option IS missing, and if consumers (that is, you) accept such computers, then Acer, and eventually other manufacturers, will continue (or begin) to deliver computers with this critical feature unavailable. Given the nature of what companies are, the only way you'll catch their attention is with a return; a return costs them money, which a letter of complaint doesn't. If they start seeing returns because users can't get Ubuntu (or other Linux distributions) to boot on their computers, they may pay attention. If they don't see returns or if they don't know the cause of the returns, it will be Business as Usual.
A second caveat on this is that Ubuntu should support Secure Boot. There are cases where it doesn't work, though, and your description sounds like this is one of those cases. Without having the computer in my hands I can't really diagnose this further. Depending on the nature of the problem, there may be workarounds that would enable you to install Ubuntu even on your computer -- or perhaps I should say that there may be workarounds that would enable me to do it. I maintain the rEFInd boot manager, and added Secure Boot support to it, so I've got expertise in this area that most people lack, and it would take my level of expertise to find and use the relevant workarounds.
In sum, there are three possibilities:
- You've missed the option to disable Secure Boot. If you can find it, you can install Ubuntu with Secure Boot disabled.
- There's a workaround that would require considerable expertise to locate and use. This level of expertise cannot be expected of normal users, so the computer should be returned as unsuitable for your uses.
- There is no workaround and no way to disable Secure Boot, in which case the computer is 100% incompatible with Ubuntu, and you should return it.
In either of the "return" cases, it's imperative that you tell Acer why you returned the computer, so that they're motivated to fix their firmware.
You may also want to file a bug report against Ubuntu. As I said, in theory Ubuntu should work on a computer with Secure Boot active. If it doesn't, that's a bug. Be sure to include the exact model number in your bug report. (Acer's Web site shows several "E1" models.) In fact, I'm curious enough that I'd like to know the exact model myself.