I emailed a google drive link via webmail to download the apk file. This downloaded directly to the 'downloads' folder, accessed via the silk browser.
Then I installed with no problems so far.
Thanks Marie and the rest for the tip.
I've loved the Kindle Fire HD 10 so far, except for the lack of dropbox...now that's solved.
Lyle
[This thread is now closed by moderators due to inactivity. If you're experiencing a similar behavior, feel free to start a new discussion in the Dropbox Community here.]