Poll module overview
Things have changed in Drupal 8. Unlike Article and Basic page, Poll is not a content type that creates nodes with fields like it did in the past. "Poll" is an entity, it is the question itself.
1. Install the Poll module as you would any other module.
2. Go to /admin/content.
3. Locate the Poll tab across the top with content and comments.
4. Click +Add a poll (in other words, add a question)
5. Complete the form and Save.
6. Your question should appear as if it were a node on the Content tab or a comment on the Comment tab.
7. Click on the question and see you question as a page.
To create a poll block using the poll questions you make, do the following.
1. Go to structure>Block layout>Custom block library tab>Block types sub-tab.
2. Click on +Add custom block type.
3. Give it a label such as: Poll block and Save.
4. Click on Manage fields next to the Poll block in the list.
5. Add a reference field to other and label it Poll Question.
6. For the Type of item to reference, select Poll. If you want to have multiple questions showing in the block, change the value of Allowed number of values. Save.
7. If you want to add instructions for your users, do it now. Otherwise, save.
8. Lastly, Manage Display by hiding the body field (unless you plan on using it), hide the label to the poll question, and set the format to show the full entity. Save.
Now for the block itself:
1. Go to Structure>Block layout>Custom block library tab>.
2. Click +Add custom block
3. Select Poll block
4. Complete the form by using the Poll question reference field to reference the poll question entity you have already created.
6. Place the block in a region so you can see it.